The present invention relates to an ultrasonic transducer which transmits and receives ultrasonic wave, especially to an ultrasonic transducer for detecting an object such as an obstacle.
The ultrasonic transducer generally comprises an ultrasonic vibrator 1 for transmitting and receiving ultrasonic wave, a horn 2 and a wave guide 3 for connecting the ultrasonic vibrator 1 and the horn 2 as shown in FIG. 1. The ultrasonic vibrator 1 is conventionally disposed coaxially with the horn 2. When the conventional ultrasonic transducer having the above described construction is horizontally attached to the outer portion of a rear end of a motor vehicle for detecting an obstacle backward of the vehicle, for example, the ultrasonic vibrator 1 is directly splashed with rain water or vehicle washing water which enters through the horn 2. And the water droplets adhered to the ultrasonic vibrator 1 are not easily removed. Consequently, the transmitting and receiving sensitivity of the ultrasonic vibrator 1 becomes lower and the life of the ultrasonic vibrator 1 is decreased due to the corrision thereof.
One object of the present invention is to provide an ultrasonic transducer which is suited to be disposed in a place exposed to rain water or the like.
Another object of the present invention is to provide an ultrasonic transducer having such a construction that the ultrasonic vibrator thereof is not splashed with water such as rain water and vehicle washing water which enters into the horn or the wave guide.